Multiple Vulnerabilities in ssmtp
— GLSA 200404-18

There are multiple format string vulnerabilities in the SSMTP package,
which may allow an attacker to run arbitrary code with ssmtp's privileges
(potentially root).

Affected Packages

Package

mail-mta/ssmtp on all architectures

Affected versions

<= 2.60.4-r2

Unaffected versions

>= 2.60.7

Background

SSMTP is a very simple mail transfer agent (MTA) that relays mail from the
local machine to another SMTP host. It is not designed to function as a
full mail server; its sole purpose is to relay mail.

Description

There are two format string vulnerabilities inside the log_event() and
die() functions of ssmtp. Strings from outside ssmtp are passed to various
printf()-like functions from within log_event() and die() as format
strings. An attacker could cause a specially-crafted string to be passed to
these functions, and potentially cause ssmtp to execute arbitrary code.

Impact

If ssmtp connects to a malicious mail relay server, this vulnerability can
be used to execute code with the rights of the mail sender, including root.

Workaround

There is no known workaround at this time. All users are advised to upgrade
to the latest available version of ssmtp.

Resolution

All users are advised to upgrade to the latest available version of ssmtp.